C# | Get or set the element at the specified index in ArrayList (original) (raw)

Last Updated : 20 Jun, 2022

ArrayList.Item[Int32] Property is used to get or set the element at the specified index in ArrayList. Syntax:

public virtual object this[int index] { get; set; }

Here, index is the zero-based index of the element to get or set. Return Value: It returns the element of Object type at the specified index. Exception: This property will throw ArgumentOutOfRangeException if the index is less than zero or is equal to or greater than Count. Below programs illustrate the use of above-discussed property: Example 1:

CSharp `

// C# code to get or set the element at // the specified index in ArrayList using System; using System.Collections;

class GFG { 

// Driver code 
public static void Main() 
{ 

    // Creating an ArrayList 
    ArrayList myList = new ArrayList(); 

    // Adding elements to ArrayList 
    myList.Add("A"); 
    myList.Add("B"); 
    myList.Add("C"); 
    myList.Add("D"); 
    myList.Add("E"); 
    myList.Add("F"); 

    // Displaying the elements 
    // in the ArrayList 
    foreach(string str in myList) 
    { 
        Console.WriteLine(str); 
    } 

    Console.WriteLine("After Item[int32] Property: "); 

    // setting the value at index 2 
    myList[2] = "Z"; 

    // Displaying the elements 
    // in the ArrayList 
    foreach(string str in myList) 
    { 
        Console.WriteLine(str); 
    } 
}

}

`

Output:

A B C D E F After Item[int32] Property: A B Z D E F

Example 2:

CSharp `

// C# code to get or set the element at // the specified index in ArrayList using System; using System.Collections; using System.Collections.Generic;

class GFG { 

// Driver code 
public static void Main() 
{ 

    // Creating an ArrayList 
    ArrayList myList = new ArrayList(); 

    // Adding elements to ArrayList 
    // Adding elements to ArrayList 
    myList.Add(2); 
    myList.Add(4); 
    myList.Add(6); 
    myList.Add(8); 
    myList.Add(10); 
    myList.Add(12); 
    myList.Add(14); 
    myList.Add(16); 
    myList.Add(18); 
    myList.Add(20); 

    // Displaying the elements 
    // in the ArrayList 
    foreach(int i in myList) 
    { 
        Console.WriteLine(i); 
    } 

    Console.WriteLine("After Item[int32] Property: "); 

    // setting the value at index 8 
    // this will give error as index 
    // is greater than count 
    myList[10] = 56; 

    // Displaying the elements 
    // in the ArrayList 
    foreach(int j in myList) 
    { 
        Console.WriteLine(j); 
    } 
}

}

`

Runtime Error:

Unhandled Exception: System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index

Time complexity: O(n) for traversing ArrayList

Auxiliary Space: O(n) where n is the size of the ArrayList

Reference: